Chair assemblies with rockable backs



y 1962 A. MASSEN 3,036,863

CHAIR ASSEMBLIES WITH ROCKABLE BACKS Filed Feb. 1, 1960 4 Sheets-Sheet 1INVENTOR. ARMAND HAssEN BY 77 9, 2026 0 Samar,

ATTORNEYS May 29, 1962 A. MAssEN CHAIR ASSEMBLIES WITH ROCKABLE BACKS 4Sheets-Sheet 2 Filed Feb. 1, 1960 m w G L a k w m e i m.... mm

ATTORNEYS May 29, 1962 A. MASSEN CHAIR ASSEMBLIES WITH ROCKABLE BACKS 4Sheets-Sheet 3 Filed Feb. 1, 1960 INV EN TOR.

ARMAN D MAS$EN ATTORNEYS May 29, 1962 A. MASSEN CHAIR ASSEMBLIES WITHROCKABLE BACKS 4 Sheets-Sheet 4 Filed Feb.

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W W M M D M 6% M 1 A Y B AT TO ZNEYS 3,036,863 CHAIR ASSEMBLIES WITHRGCKABLE BACKS Armand Massen, Staten Island, N.Y., assignor to The S. S.White Dental Manufacturing Company, Philadelphia, Pa., a corporation ofPennsylvania Filed Feb. 1, I960, Ser. No. 5,679 11 Claims. (El. 297-374)This invention relates to chair assemblies having seats and backs whichcan be rocked relative to the seat; and is particularly of value forservice chairs such as those used by dentists.

Such general arrangements are known and in use. It is desirable that theservice attendant, e.g., the dentist, be able to adjust the back whilethe chair is occupied: and that the back be rigidly fixed, relative tothe seat, in the selected position.

An object of the invention is the provision of a chair assembly in whichthe pivotal parts are covered by the seat, both for concealment and forpreventing injury to the occupant'or attendant.

Another object is the provision of a chair assembly in which trunnionpivots are employed between the seat and back, with friction means toprevent sudden and uncontrolled relative movements when the lockingdevice is released, and with counterbalancing means associated withpivotal members to reduce the effort involved in adjusting the backposition.

Another object is the provision of a chair assembly in which theposition fixing or locking device for a movable back includes aself-adjusting member whereby wear is automatically compensated.

Another object is the provision of a chair assembly in which a positionfixing or locking device is provided for the seat and back, withoppositely acting locking parts operative upon a self-adjusting memberbetween them whereby equal locking efforts are exerted by the parts.

With these and other objects in view, as will appear in the course ofthe following description and claims, an illustrative embodiment isshown on the accompanying drawings, in which:

FIGURE 1 is a side elevation of a chair assembly, with one position ofthe back shown in full lines, and another position shown in dottedlines;

FIGURE 2 is a top view of the chair of FIGURE 1;

FIGURE 3 is a top View, on a larger scale than in FIG- URE 2, with theseat portion removed;

FIGURE 4 is a section on line 44 of FIGURE 3, showing the trunnionsystem;

FIGURE 5 is a section on line 55 of FIGURE 3, showing a counterbalancearrangement;

FIGURE 6 is an upright section on line 6-6 of FIG- URE 3, showing alocking member;

FIGURE 7 is a rear view substantially in the direction of the arrow '7in FIGURE 1, of the back portion, with parts broken away to show partsof the locking arrangement and its actuator;

FIGURE 8 is a sectional view on line 88 of FIG- URE 3;

FIGURE 9 is a perspective View of locking parts, with a locking sectorin dotted lines.

The illustrated chair is for dentists use; and has a base 10 formounting on a fioor, with a telescoping column 11 rising therefrom andhaving at the top a support member 12 on which is mounted by atransverse pivot a seat frame 13 which can be tilted, and fixed inposition, illustratively by the parts 14. A foot rest and arm restassembly 15 is fixed to the frame 13 to move therewith. A tilting back16 is pivoted relative to the frame 113 so that it can occupy variouspositions such as those shown by the full and dash lines in FIGURE 1.Arms nited States Patent 0 17 are pivoted to the assembly 15 forcontrolled rocking movement.

According to this invention, a locking back support member 20 isconnected fixedly to the back, and, FIG- URES 3 and 6, has laterallyextending arms 21 which have pivot shaft 22 fixed thereon and rotatablein the side wings 23 illustratively formed integral with the frame 13and providing trunnions between the seat and back structures. Downwardextensions 24 of the arms 21 carry pivots 25 at their lower ends, whichproject laterally outward through arcuate slots 26, FIGURE 6. Links 27are connected at pivots 25 and extend relatively forward, and arepivotally connected to blocks 28 which can slide in the tubes 29 fixedon the frame 13 inside the laterally and forwardly extending side plates33 fixed to the frame 13. As shown in FIGURE 3 for one of the tubes 29,compression springs 31 are within the tubes 29 and effective for urging.the blocks 28 toward the rear, i.e., toward the left in FIGURES 1, 3 and6, and reacting against threaded plugs 32 in the front ends of thetubes: by adjustment of the plugs 32, the effort of the springs can beregulated to determine the return of the back 16 from the dotted linetoward the full line position of FIGURE 1, thereby providing acounterbalance for the weight of the back.

It is preferred to provide a darnpener for the otherwise free pivotaltilting movement of the back. This is illustratively attained at thepivot shafts 22, FIGURE 4, by forming these shafts with stems 22a whichclosely fit the wings 23 and with threaded portions 22b extending beyondthe inner faces of the arms 21, for receiving the nuts 220. A frictionwasher 34 is interposed between the respective wings 23 and associatedarms 21. The nut 220 is drawn tight, until the frictional effectrequires a force of, say, 4 to 7 pounds to be exerted at the head restpivot, with the head rest at its highest and most extended position andwith the tilting back at about 60 degrees to the horizontal.

The lower rear cross-member 35 of the frame 13, FIG- URE 6, provides arail along which the locking sector plate 36 for the tilting back maymove from side to side. This sector 36 is bifurcated at its lower end toengage the member 35, and is thereby prevented from moving upward,downward or forward. The sector 36 extends arcuately about the trunnionaxis at shafts 22, and at its upper and rear end is guided by the lowerstu'face of the rear upper cross-member 37 of the frame 13 and is herebydetained against upward movement. A transverse notch in the upper end ofthe sector 36 receives a guide pin 38 mounted on the cross-member 37,FIGURE 6, and is thereby detained against forward or backward movement.The sector 36 can move transversely along the cross-members 35 and 37.

The back support Ztl, FIGURE 6, is rigidly connected to the lower end ofthe back frame 41 by screws. The sector 36 fits loosely in an uprightgroove in the front part of the support 29, for permissive transversemovement relative thereto, with the root of the groove having partsloosely conformed to the outer or rear edge of the sector.

The back support 20 has opposed projections 44 at the two faces of thesector 36 and spaced therefrom. The inner surfaces of the projections44, FIGURE 8, converge upwardly. Locking rollers 45 are located betweenthe projections and the respective adjacent surfaces of the sector 36. Astop block 46 extends through an aperture 47 of the support 20, beingguided at its sides for relative upward and downward movements, and isbifurcated at its front end to provide fingers 48 which extend betweenthe projections and the respective sector surfaces, and have holes forreceiving the rollers 45. Springs 49 urge the fingers 48 upward, forengaging the balls in wedging position between the surfaces and therebypreventing rearward rocking of the back relative to the seat. The lowerends of the springs 49 are guided in pockets in the support 20, andreact against plugs 50 threaded into these pockets.

The stop block 46 has a rearward projection 51 located beneath a pin520: on a lever 52 pivoted at 53 on the back frame at one of the leverends, and connected to a link 54 at the other lever end. The link 54extends upward in the back structure, and includes a turnbuckle 55 bywhich its length may be adjusted. The upper end of the link 54 isconnected to a crank lever at a horizontally extending leg 56 thereof.The crank lever has a pivot mounting 57 on the back frame, and its otherleg 58 extends outward through the back frame structure and upward forready access by the dentist. A weak spring 59 urges the leg 58 to moveso that the lever 52 holds its actuator pin 52a in contact with theprojection 51 on the block 46.

As shown in FIGURES 1, 2 and 6, a seat 60 covers the seat frame 13between the lateral projections 61 which carry the chair arms, andextends from the back structure to a point above the drop portionleading to the foot rest. This seat is illustrated, FIGURE 6, as formedof sheet metal with a skirt portion 62; and covered with fabric 63 overa rubber cushion pad 64. At the rear, an inturned lower edge of theskirt 62 engages hooks 65 on the seat frame: at the front, theupstanding spring clips 66 yield when the seat is forced over them, andthereafter hold it removably in place. At the sides, the lower edge ofthe skirt 62 can rest on rubber bumper blocks 67 extending (FIGURE 3)from the sheet metal side trim pieces 68, so that the seat 60 overlapsthe outer parts of the trim pieces. In FIGURES 2, 4 and 6, it will benoted that the working parts of the seat and back pivots are all beneaththe seat, being concealed thereby so that the seat prevents accidentalcontact by the occupant with such parts by his body or hands, andtherewith providing a generally smooth external appearance without theencumbrance of any projecting parts except the arms and back structure.The manual control lever part 58 is behind the back cushion, and is notaccessible to an occupant who is in normal positon in the chair; andalso is not in position for accidental contact by the dentist.

In operation, the back is normally urged toward the full line position,FIGURE ;1, relative to the seat by the action of the counterbalancingsprings 31, under control by the friction elfect at the washers 34. Thelocking rollers 45 are in raised position and wedged between theprojections 44 on the back and the sector 36 held by the seat frame, sothat backward pressure on the back structure does not cause a rearwardand downward tilting thereof. If such tilting is desired, so that theback will be at a more horizontal position relative to the seat, thedentist presses the accessible manual control leg 53 inward toward theaxis of the back assembly. Therewith, the link 54 is forced downward,and rocks the lever 52 downward, so that the block 46 is moved downwardand its fingers 48 press the rollers 45 downward from their lockingposition, thereby releasing the support so that the back assembly may bepushed backward about its trunnions, wherewith the extensions 44 fixedto the support 20 and wings 21 act to move the links 27 and blocks 28forwardly, compressing the counterbalance springs 31. Upon releasing themanually operable leg 58, it is moved outward by spring action, and therollers 45 are lifted by the springs 49 by means of the fingers 48 andagain lock the support 20 to sector 36, against further rearwardtilting. When in a rearward tilted position, the back structure can beshifted toward a more upright position, by pressing the upper end of theback structure forward, with the weight of the patient against it,noting that part of the returning efiort is being exerted by thecompensating springs 31. Therewith, the projections 44 of the support 20are being lifted relative to the rollers 45 so that the latter do notprevent the movement: if the back is i lifted only part way toward thefull line position, FIG- URE 1, the rollers 45 immediately engage againand preserve this position.

The permissive lateral or transverse movement of one of the lockingmembers, illustratively the sector 36, relative to its support, effectsan automatic adjustment of the relative efforts of the rollers 45'. Forexample, if the left hand roller in FIGURE 8 for any reason exerts agreater pressure against the sector 36 than the right hand roller, thesector yields transversely until the efforts are balanced. This avoidsthe need of any careful balancing adjustment for such forces, andprovides automatic compensation in the event of greater wear at one sidethan at the other, at the surfaces of the sector 36 or the projections44.

The invention is not limited to the illustrative embodiment; and can beemployed in many ways within the scope of the appended claims.

What is claimed is:

1. A chair assembly with a rockable back, comprising a seat port-ion anda back portion, a pivot member connected to the back portion andcooperative pivot parts connected to the seat portion, said pivot memberhaving a radially projecting arm, a sleeve fixedly. connected to theseat portion against movement relative thereto upon rocking of the back,a compression spring within the sleeve, and a connection from said armfor compressing said spring when the back portion is rocked backwardrelative to the seat portion.

2. A chair assembly as in claim 1, in which a threaded member isreceived within the tube for receiving the reaction of the compressionspring, and is adjustable along the tube for regulating the forwardlyreaching effort exerted by the spring.

3. A chair assembly with a rockable back, comprising a seat portion anda pivotally mounted back portion; an upright plate held by the seatportion with permissive transverse movement, said seat portion havingparts for preventing rocking of the plate relative to the seat portionabout the piovtal axis for the back portion, a stop block carried by theback portion for upward and downward movement relative thereto, saidblock having fingers extending at opposite faces of the plate, andlocking devices carried by the fingers for engaging the opposite facesof the plate; parts connected with the back portion and effective toengage said locking devices with the plate for preventing rocking of theback portion in one direction, means for urging the block into lockingposition, and means for moving the block from locking position.

4. A chair assembly as in claim 3, in which the said urging meanscomprise springs seated on the back portion.

5. A chair assembly as in claim 3, in which the said moving meansincldes a projection on the block, and means carried on the back portionfor moving said block against the action of said urging means.

6. A chair assembly as in claim 5, in which the said means carried bythe back portion includes a lever having a part movable therewith topress against said block projection, a link connected to the lever andextending upward, and a second lever pivoted on the back portion formoving said link.

7. A chair assembly with a rockable back, comprising a frame, a seatportion having a top and sides held against movement relative to theframe, a back portion, a pivot member connected to the back portion andextending beneath the top of the seat portion, cooperative pivot partson the frame and located beneath the top and between the sides of theseat portion, a crank arm connected to said pivot member, spring meansconnected between the frame and said crank arm for causing upwardswinging of the back portion, friction brake means associated with saidpivot member and parts for estricting rocking movement of the backportion relative to the seat portion, and means on the frame and pivotmember for holding the back portion in adjusted position independentlyof the action of said friction brake means.

8. A chair assembly with a rockable back, comprising a frame, a seatportion on the frame, a back portion including a pivot member fixedthereto and extending beneath the seat portion, pivot parts located onthe frame beneath the seat portion and cooperative with said pivotmember, a plate mounted on the frame for permissive lateral movement andextending radially relative to the axis of said pivot parts, parts onthe frame for preventing rocking movement of the plate relative to theseat portion, opposed friction devices on the back portion for engagingsaid plate at opposed surfaces thereof, and manually operable means forcontrolling the engagement of said friction devices with the plate.

9. A chair assembly, comprising a frame, a seat portion mounted on theframe, a rockable back portion and a pivotal connection therefor mountedbelow the top of the seat portion, a plate secured against rockingrelative to the frame about the pivot axis, a member carried by the backportion in its rocking movement and having projections located atopposite sides of the plate, spaced plate-engaging means located betweensaid projections and movable upward and downward on the back portion,first means for moving the said plate-engaging means upwardly relativeto the back portion, said projections having parts cooperative with theplate-engaging means for causing the latter to lock with the plate andprevent backward rocking of the back portion upon such upward movementthereof, and a manually operable second means effective for moving saidplate-engaging I means downwardly and thereby releasing the back portionfor rearward rocking.

10. A chair assembly as in claim 9, in which the frame has transverseguideway means, and the plate is carried on the guideway means andthereby held against rocking about the pivot axis but with a permissivetransverse movement along the pivot axis, in which the said cooperativeparts on the projections are upwardly convergent surfaces, and the saidplate-engaging means are located for respective wedging between asurface of the plate and one of said surfaces upon upward actuation bysaid first moving means, and wherein the plate can adjust itselftransversely under unequal forces exerted by said plate-engaging meansfor balancing said forces.

'11. A chair assembly with a rockable back, comprising a seat portionand a back portion, the seat portion comprising a frame and a removableskirted seat for covering the frame, said back portion including a pivotmember extending beneath the seat portion, pivot parts on the seatportion cooperative with the pivot member, said pivot member and partsbeing located between the side portions of the seat skirt and concealedby the seat when the latter is in place, a plate mounted on the seatportion for lateral movement and restrained from rocking movement withthe back portion, opposed friction devices on the back portion forengaging said plate at opposed surfaces thereof, manually operable meansfor controlling the engagement of said friction devices, a sleeveconnected to the frame, a compression spring in the sleeve, a radiallyprojecting arm on said pivot member, and a link connected to the arm forcompressing the spring when the back portion is rocked backward relativeto the seat portion.

References Cited in the file of this patent UNITED STATES PATENTS

